Genetically Engineered Mouse Models

C57BL/6J mice (CD45.2) were purchased from Envigo and housed in individually ventilated cages under SPF conditions. Ccr2^−/− animals (originally from The Jackson Laboratory; Boring et al., 1997 (link)), Cx3cr1^+/GFP (available from The Jackson Laboratory and provided by S. Jung; Jung et al., 2000 (link)), and congenic CD45.1 mice (serially backcrossed from SJL/J onto C57BL/6) were all bred in-house and shared by K. Else, K. Couper, and A. MacDonald (University of Manchester, Manchester, England, UK), respectively, and were backcrossed to a C57BL/6 background for at least 10 generations. Cx3cr1^CreER mice (from The Jackson Laboratory; Yona et al., 2013 (link)) were bred in-house crossed with R26-yfp mice (from The Jackson Laboratory; Srinivas et al., 2001 (link)) and were backcrossed with C57BL/6J for at least six generations. For GF experiments, all mice including SPF controls were bred in-house and were on a C57BL/6 background. GF C57BL/6 mice (founders from the Clean Mouse Facility, University of Bern, Bern, Switzerland) were bred and maintained in The University of Manchester gnotobiotic facility. SPF controls were also housed and maintained on the same diet and light cycle as GF animals. All experiments were approved by The University of Manchester Local Ethical Review Committee and were performed in accordance with the UK Home Office Animals (Scientific Procedures) Act 1986.